1.Field of the Invention
The present invention relates to communication systems in which remotely stored programs may be grabbed for locally converting a microcomputer controlled terminal into a selected purpose variable function terminal whose selected function may be locally changed.
2. Description of the Prior Art
Computers and other types of programmable devices are well known in the data processing art and in the communications field in general. These prior art systems function in accordance with a stored set of instructions or programs or a series of programs, such as in a typical IBM Operating System or OS. In such systems, however, the programming is accomplished at the central computer whose function may be varied only by variation in the program which is loaded thereinto. Due to the high cost of computers, the art of time sharing has developed which, through teleprocessing, has enabled a plurality of users to share a common centrally located computer by use of remote input/output devices. However, such time sharing still requires the users to be bound by the particular program which is stored in the central computer so that the plurality of users essentially share the same program functions which process their individual data inputs in accordance therewith. There are presently no systems known to the inventor in which remote local terminals connected to a remote central data source can function in accordance with any one of a plurality of locally selected purposes or functions to provide a selected purpose variable function terminal in which the selected purpose or function may be locally varied electronically without the user having to actually reprogram his terminal. Furthermore, there are no such terminals known to the inventor in which a video communication system which enables the video display of information, such as over a CATV system, may also be converted to a local selected purpose variable function terminal in which desired control programs may be electronically called up or retrieved from a remote central processor for local storage and operation in accordance therewith. Such a video communication system in which individual frames may be grabbed for video display thereof and updated on a row-by-row basis is described in my previously issued U.S. Pat. No. 3,889,054, issued June 10, 1975, in which pseudo video digital data scan lines are transmitted continuously from a central data source in a one way communication system. Such a system may be controlled locally by a microcomputer as described in my copending U.S. patent application entitled "Improved Row Grabbing System", filed Sept. 10, 1975, bearing U.S. Ser. No. 611,843. As will be described herein, such video communication systems, as those employing a local microcomputer, have not been utilized to full advantage as a selected purpose variable function terminal in which processing of data in accordance with any desired selected function, which may be varied, can be accomplished as well as the display of video data therefrom. The present invention is an improvement on such systems so as to provide such a selected purpose variable function terminal.